Parenteral magnesium oxytetracycline acetic or lactic acid carboxamide vehicle preparation



2,980,584 Patented Apr. 18, 1961 PARENTERAL MAGNESIUM OXYTETRACYCLINE ACETIC R LACTIC ACID CARBOXAMID VEHICLE PREPARATION 5 Claims. '(Cl. 167-65) This invention is concerned with new and. novel liquid two molecules of the base employed in adjusting the pH.

' Useful neutralizing agents include ammonia and the antibiotic compositions adapted for parenteral administrathe antibiotic and a metal salt dissolved in anaqueous lower aliphatic carboxamide. These preparations possess physiologically acceptable lower aliphatic water soluble amines having dissociation constants greater than about 10- whose salts of the oxytetracycline complex formed are soluble in the vehicle employed. Weaker bases are not satisfactory since they do not form the required com plex salts. Metal hydroxides and basic salts are less desirable since they frequently yield antibiotic complex salts which are not sufiiciently soluble in the vehicle and also involve the injection of additional metal ions. For example, sodium hydroxide leads to the formation of a precipitate, which is thoughtto be the disodium salt of the oxytetracycline complex, when it is attempted to prepare a solution having an oxytetracycline concentration of 50 mg./kg More dilute solutions can, however, be prepared satistion, is determined by. a'series of simple experiments to select the proportion. having satisfactory solubility. Magne'sium chloride isthe preferred metal saltfor use inthe present compositions, since no adverse physiological ofunique advantages and'represent a definite improvement over prior compositions both with regard to shelf stability and compatibility with the tissuesjon intramuscular injection... 4

Although oxytetracycline may .beinjected intramuscularly as the base or as an acid addition salt'v vith"the achievement"o fi antibiotic blood levelsjin the systc'm,-it has been found that appreciable irritation often-accompanics such injections and particularly if repeated injections are made at the same point or at places close to the original injection. Furthermore, thereis a tendency for residual material to remain in the muscle at the, side 'of Anions other than thechloride, that is magnesium salts fectsi result from its injection, and a stable, pharmaceutically elegant preparation is obtained. Two thirds of a moleof this and other magnesium, salts per mole of oxytetracycline is required. Some variation from this precise ratio is possible up to about an equimolar amount. Thus,

the range of 0.67 to 110 molar equivalents of magnesium salt per mole of oxytctracycline is operative.

other than magnesipmfchloride, can be employed. It is only necessary that the salt provide a clear solutiorrand that, of, course, ,the anion be physiologically, acceptable, Tco'mpatible in solution with the oxytetracycline, and stable at the pH of the composition. Satisfactory results are achieved by substituting the gluconate,'acetate,jsulfate,

improve the degree of absorption ,andreduce the irrita- M tion caused by the antibiotic.- .Such formulations are, however, stable for'only short periods oftime when dissolvedin water and, therefore, solutions thereof must be prepared ,bythe physician immediately Ipriorlto use. While'such a; mode,of administration is adequate, it is I quite inconvenient, and in additienuse under, adverse circumstances pioyides opportunity, for contamination by dirtor microorganisms as ,well as ;for error... Inorder to overcome these disadvantages, solutions of oxytetracycline in various vehiclesflhavebeen sugg'ested, in"the past. but

glucoheptanate, phosphate, etc. for the. chloride. 'ByapIf propriate adjustment of thevehicle amide concentration, pH, and metal/salt antibidticratio, the corresponding Cali fciulm, Zinc, "aluminum, and manganese? salts can be substituedforrna'gnesium chloride; a I

The vehicle of, the unique compositions offthe' present invention is 'an aqueous solution of a physiologically ac}- ceptabledower aliphatic carboxamide and preferabl amide .of acetic of. lactic acid. The carboxamidehas a '{cbnc'entration inthe -range of 25 to 80% by weightof the vehicle, the preferred value being by weight.- At

none been satisfactory from the standpoint of'tissue irritation,f"absorptionon stability. H

Anobject ofthe present invention, therefore, is to'p'rovide stable solutions of oxytetracycline which are nonintrarnuscularfinjection, and shelf irritating upon intramuscular injectioniand from which the antibiotic activity is readily absorbed into theblood stream ofthe'animal organism; Further objects will'be apparent from the following disclosure.

It has now been found that aqueous solutions containing a substantial proportion of a' physiologically acceptjable, water. soluble, "lower aliphatic amide provide remarkably stable oxyte'tracyclinej:solutionshaving relativelyhighconcentrationsof'antibiotic when precise proportions of adivalentmetal salt and a pilot at least about T1815 is employed. It is thought that this remarkable stability advantage over other solutions having relatively slight differences in composition and pH is due to th'e 'form'ation of a specific oxytetracycline me'tal' complex. -T his complex is thought to have thecompositionofi three piolecules of oxytetracyclinetoxtwo. atoms .of metal and the contents of parenteral 7 drugs.

lower concentrations, the solubility and stability ofthe antibiotic is reduced. 1 At amide concentrations. exceeding 8( )%,'t he'so'lvent becomes irritating and not well tolerated jon injection. At the preferred value of 5 0%. by weight of carboxamide, thejyehicle has'excellent solvent ,characterf 'isticsjati'the desired pH. for the antibiotic and salts in 'volved inthe composition and the composition is'falso well tolerated upon intramuscular injection. .iThisv vehicle can also be employed intravenously when the "concentrated ipreparation is' diluted with an appropriate quantity of saline or ptlier diluent used in intravenous therapy. Suitable amides for the vehicles a of the present compositions include I"N,N=dietliylacetamide; N,N -dimethylacetamide,-

droxyethynlactamide. 1in g'enerahfi 'any of the lower 7 aliphatie carboxa-mides canbe employed so long as they f are not toxicfare .not irritating, and are solvent s 'forthe Y ."oxytetracyc'line and salts of the compositionl In general, tthe:'-latter causes no difiiculty, butthe 'question of physio logical compatibility must becarefully; evaluatedfkon sidering' as well prevailing governmental-restrictionsfon One of the ditfifulties en 'oun'te red with aqueohs lli'qui d compositions of oxy'tet'racycline is discoloration andflgis's" of potencyiwhich appears to be due jin Ii'artftdoxidative with aqueous solutions, but is also occasionally encountered with aqueous suspensions. In order to avoid this diflicul-ty, oxidizing conditionsmustbe avoided during storage'of the present product. To this end, oxygen is excluded from the finished solution and antioxidants are sometimes included in the solution. Antioxidants are not necessary ifoxygen has been rigorously excluded by maintaining the product in an inert atmosphere such as an atmosphere of nitrogen, helium, or other IlOH-OXl'. dizing, non-reactive gas. Carbon dioxide is a non--oxi dizing gas useful in many such operations but it is not satisfactory in the present case due to the alkaline pH of the solution. Formation of carbonate salts of the basic agents that are employed in adjusting the pH of the composition may occur.

7 As a practicalmatter, itis convenient to employ antioxidants in addition to manufacturing and storing the product in an inert atmosphere. Satisfactory antioxidants are those which are physiologically acceptable for use in parenteral drug products and those which are, of course, compatible with oxytetracycline. Examples of suitable antioxidants include sodium bisulfite, sodium metabisulfide, and sodium formaldehyde sulfoxylate. Sodium ascorbatewhich is physiologically acceptable as ari antioxidant, is not sutficiently stable at the pH, em-

- ployed. Concentrations of the above antioxidantswhich scape at 100 mgJml. when intramuscular injection is the purpose for which the compositions are intended. This is the primary use for which they are adapted. However, they are equally adapted to intravenous administration when diluted with water or diluents employed in intravenous therapy such as isotonic" glucose, saline, or Ringers solution in appropriate quantities. For this use, initial concentrations down to about 10 to 25 mg./ml. of the anti biotic are satisfactory. In preparing these relatively dilute solutions for intravenous therapy, inorganic bases such as sodium hydroxide, sodium carbonate, and sodium phosphate can be used for neutralization.

The dosage of the present compositions is adjusted to provide fromlOO mg. to about 500 mg..of oxy tetracycline activity per day for the average adult. Similar or reduced doses may be employed in the treatment of chilare effective and still in' accordance with governmental regulations for parenteral products are employed in the present formulation. Forv example, sodium bisulfiteis employed in about 0.1% concentration. Generally from about 0.05 to 0.2% concentrations of antioxidant are r aqueous solution in appropriate quantity. The pH of the mixture is then adjusted to about 8.5 with ammonia ora physiologically "acceptable-lower aliphatic amine, pref erablyethanolamine." The pH of the'final composition is critical as is the metal saltconcentration. The pH must beat least about 8.5 in order to effect solution of all the pHs alsov provide. stable solutions but ,as the pH is increased, abovev about 9.5,"the physiological compatibility of. the'product with the muscle tissue is decreased. Slightly lower or slightly higher pHs may be employed but thesatisfactory range issubstantially from 8.5 to 9.5. .A great'variety of lower aliphatic primary, secondary, and tertiaryamines having up to about 6 carbon atoms per groupattached to the amino nitrogen atom, can beused for the neutralization stepincluding ethanolamine, di-

the invention in anyway.

Example I A composition of the present invention containing the following ingredients is prepared in the following fashion.

Amphoteric oxytetracycline (assay 910 meg/mg.) 22 g. Magnesium chloride hexahydrate 6 g. :Eth'anolamine, 20% aqueous 29 ml. (suflicient V to adjust the Y I pH to 8.5). Sodium formaldehyde sulfoxylate 800 mg. N,N-dimethylacetamide ca. 180 g.

Water, pyrogen free .ca. 180 ml.

The oxytetracycline and magnesium chloride are mixed with 320 ml. of a 1:1 solution (w./w.) of the dimethylacetamide in water. The pH of this solution isthen adjusted to 7.0 with theethanolamine solution, andthe sodium formaldehydesulfoxylatev added, The suspension is then adjusted to pH 8.5 with, the remainder of the 'ethanolamine solution, thoroughly mixed until solution components. T This is, in fact, the preferred'pI-l. Higher ethylamine, .ethylamine, triethanolarnine, diethanolamine,

arginine, glucosamine, etc. must, of course, be sterile. Thus, sterile components and 1 conditions ofmanufacture are, employed, or alternatively, thesolution' itself is sterilized, for instance, by filtration as a final stage of manufacture: The latter offers a'number ,5;

of practical advantages.

i The use of an acid addition saltrof the antibiotic such, as. oxytetr'acyclinehydrochloride,'oxytetracycline phosphate,- oxytetracyclinef nitrate, etc. in preparing the pres.-

ent compositions issatisfactory; However, they require; a largeramount of neutralizing agent with the 'accom-f panying formation of; a' larger quantity of the by-product The. finished composition acid addition saltof'the neutralizing agent.-; excess material performs no physiological function and, there-,

' fore,'it is preferred to use the ampho'teric antibiotic and keep'the total concentration of the solution to a minimum.

eypreferred concentration of oxytetracycline is 50 to occurs and diluted to 400 ml. with the balance of the 1:1 dimethylacetamide water solution. The finished formulatron contains 50 mg./ml. of oxytetracycline activity. The

'batchis sterilized by filtration, subdivided into 2 ml.

u tients, it Iis'injected intramuscularly in,2 ml. doses;

This preparation was tested for absorption and tissue irritation in rabbits. Albino rabbits were used in this experiment, each receivinga l ml. injection of the composition in the gluteus 'maximus muscle. The animals were sacrificed 24 hrs. .after injection and the muscle examined for irritation and degree of absorption. Gross examination ofthe degree of absorption *Was. made by noting the amount of injected materialremaining in the areaofjinjection. The muscles were then fixed in 10% 1 neutral buffered formalin and examined for lesionsbythinly slicing .each' 'muscle.r The present -fc rmulationY.-

caused-only slight irritation withno grosseviden'celof any tissue change and only a slight increase in redness of the injected: area; 75%".01 more of the preparation:

was absorbed vin i'24 hours. An even higher degree. of absorption is obtained by using an additional 10% by weight of magnesium chloride- Blood level determinations in rabbits, were performed to verify the observations regardiu'g' absorption. 1 At 'aEf for the oxytetracycline to epirmerize.

, dosage of 6.25 'mg./kg., a blood serum level of2.63 mcg./ml. was noticeable after 1 hour. This blood level ,was maintained then for approximately 5 hours at which time a gradual decrease was observed to 1.5 meg/ml. 7 hours after injection, and 0.883 mg./ml. after 18 hrs. After 24 hours, a blood level of 0.l83mcg./ml. was detectable. The blood level results are substantially equivalent to those obtained using a commercial oxytetracycline intramuscular preparation comprising a mixture of oxytetracycline hydrochloride and magnesium chloride in the dry condition which was diluted with water prior to injection.

Each of a group of patients was given an intramuscu- Stability Results; Bioassay (meg/ml.)

I ture Tempem Initial 1 Week 4 Weeks 6 Weeks 17 7 Weeks 50 0 s7. 0 so. 9 33.3 29. 4 14.0 37 C 35. 4 34. 8 27. 0

Thus in the 50 study, this sample lost approximately 60% of its original biological activity in 17 weeks. On

' the other hand, the potency of the composition of the last injection consisting of 2 ml. of the above formulation. Blood samples were then removed, at intervals of 1, 2, 4, 6 and 8 hours following injection and the serum concentration of antibiotic determined. Of patients, the following average values for the blood levels were obtianedi 1 hr., 0.917 mcg./ml.; 2 hrs., 1.007 mcg./ml.; 4 hrs., 1.078 mcg./ml.; 6 hrs., 1.020 mcg./m1.; and 8 hrs., 1.166 meg/ml. A control experiment employing eight patients to which a commercial oxytetracycline formulation .was administered was carried out.

This commercial formulation consisted of a mixture of Stability Results; Bioassay (mg/ml.)

Temperature Initial 1 Week 3 Weeks 6 Weeks 12 6 Mo. Assay Weeks In each preparation, the chemical assay agreed with the biological assay indicating that there was no tendency Preparations containing an additional 10% by weight of magnesium chloride have still greater stability.

The use of greater than a 1:1 molar ratio magnesium chloride to oxytetracycline and of a pH lower than 8.5 was found to have a remarkably deleterious effect on the stability of this preparation although such formulations were satisfactory from the standpoint of absorption and irritation upon intramuscular injection. Optimum stability is obtained employing about 0.74 mole of magnesium chloride per mole of antibiotic. The loss in stability in a similar preparation but at a ditferent pH The following results v and MgCl content is illustrated by the following data obtained for a similar composition containing the following materials:

Oxytetracycline hydrochloride 1.1 g.

This material was filled into 2 cc. ampoules which had been flushed with dry nitrogen gas. The following stability data was obtained:

present invention remained within 15% of the original value which is the limit of precision of the assay.

Example II A preparation identical to that of Example I, but containing 6.6 g. of magnesium chloride hexahydrate rather than 6.0 g.,was prepared. The exceptional stability of this preparation is borne out by the following tabulation of data obtained in C. storage tests.

75 0. Stabgllty Rfsults; Assay Example Ill A formulation, of the presentinvention was prepared follows: oxytetracycline hydrochloride (assay 895 mcg./m g'.),' 11.2 g., and magnesium, chloride hexahydrate, 3 g., was dissolved in ml. of water and 80 g. .offN-(fi-hydroxyethyl)lactamide was added. The soluition was adjusted to pH 8.5 with 20% aqueous ethanolyamine and diluted to 200 mL With 50% aqueous N-(flhydroxyethyl)lactamide (w./w.) at about pH 7, 0.4 g., of solid sodium bisulfite was added. This solution was then subdivided under nitrogen gas, 2 00., being placed in each ampoule.

Example IV A preparation as in Example III is prepared employing N,N-diethylacetamide as the diluent. In this instance, a 25% solution of N,N-diethylacetamide in water is prepared and the mixture of oxytetracycline hydrochloride and magnesium chloride is dissolved in approximately ml. of this vehicle. Four hundred mg. of solid sodium metabisulfite is then added and the solution adjusted to pH 8.5 with 20% aqueous diethylamine. The mixture is diluted to 200 ml. with 25 aqueous N,N-diethylacetamide.

Example V A composition is prepared containing the following materials: amphoteric oxytetracycline 22 g., magnesium chloride hexahydrate, 6 g., and sodium formaldehyde sulfoxylate 800 mg. These materials were then mixed with 300 ml. of 80% aqueous N-(B-hydroxyethyhacetamide, the pH adjusted to 8.5 with aqueous diethanolamine, and the mixture then dilutedv to 400 ml. with 80% aqueous N-(fi-hydroxyethyDacetamide solution.

Example VI A composition as described in Example I is prepared substituting 60% aqueous acetarnide as the vehicle and employing 20% aqueous triethanolamine as the neutralizing agent. 1

Example VII Compositions as described in. Example I are prepared substituting for the magnesium chloride, an equivalent quantity of magnesium acetate, magnesium sulfate, magnesium gluconate, magnesium phosphate, and magnesium glucoheptanate. q I

. ,7 xampl V .1 v The preparation of Example I is repeated employing as the. neutralizing'agent,aqueous solutions of ammonia,

ethylamine, arginine, "and glucosamine having concentrations of about 15% by weight or greater.

An alternative method of preparing the compositions of the present invention is to prepare and isolate under sterile c dit ons th plex 7 (o tet as ia hm a1) B and then dissolve it in the sterile aqueous amide vehicle along with the-antioxidant. The sterilization can also be conveniently accomplished by filtration of the addition salt thereof for the oxytetracycline component.

In such preparations thepH range of about pH 8.0 to 9.5 is employed and a somewhat higher proportion of metal salt is usually advantageous. Such solutions have stable biopotencies of the order of 60% the charged value due to C41 epimerization. In therapy, the reduced potencyv is compensated byuse of suitable overages or increased dosage. 7

What is claimed is:

1. A stable liquid antibiotic composition adapted for aqueous solution containing from 25 to 80% by weight of aphysiologically acceptable, water soluble, .lower aliphatic carboxamide selected from the group consisting .of an amide of acetic acid andan amide of lactic acid and dissolved in said vehicle from 10 to 100 mgl/ml. of a substance selected from the group consisting. of oxytetracycline and an acid addition salt thereof, from 0.67 to 1.0 molar equivalent of a water soluble, physiologically parenteral administration comprising, as vehicle, an 3:320

acceptable magnesium salt per mole of oxytetracycline, and sufficient of"alwa te'r soluble, physiologically accept; able base selected ,fifom the gr duprfco'n sisting of ammonia and a' physiologically acceptable, ater soluble lower aliphatic amine haying 'a dissociation constant of greater than 10* to provide said composition with a p Hiof about 8,5to 97.5. g

2. A composition as claimed in claim 1 wherein the physiologically acceptable saltjis magnesium chloride 3. A composition as claimed in claim 1 wherein the physiologically acceptable salt is magnesium gluconate. 4. A composition as claimed in claim 1 wherein the physiologically acceptable water soluble lower aliphatic carboxamide is N,N-dimethylacetamide. g

5. A composition as claimed in claim liwherein the physiologically acceptable .Water soluble lower aliphatic carboxainide is N-(,B'-hydro2;yethyl)lactarnide.

ReEerences Cited in the file of thispatent 7 OTHER g y Putnam et.: Antibiotics and Chemotherapy, yol. 3,No.

12, December 1953, pp. 1183-1186. H K V s enb n efi 'A-i Sai- L s Augu .9 PP- s1s-s22. W

Gans: J.A.P.A., Sci. Ed., Oct. 5, 1957, pp; 587, 591

(esp..p.589).

Ashtonz Chem. and had, Sept. 17, 1955, p. 1183. 

1. A STABLE LIQUID ANTIBIOTIC COMPOSITION ADAPTED FOR PARENTERAL ADMINISTRATION COMPRISING, AS VEHICLE, AN AQUEOUS SOLUTION CONTAINING FROM 25 TO 80% BY WEIGHT OF A PHYSIOLOGICALLY ACCEPTABLE, WATER SOLUBLE, LOWER ALIPHATIC CARBOXAMIDE SELECTED FROM THE GROUP CONSISTING OF AN AMIDE OF ACETIC ACID AND AN AMIDE OF LACTIC ACID AND DISSOLVED IN SAID VEHICLE FROM 10 TO 100 MG./ML. OF A SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF OXYTETRACYCLINE AND AN ACID ADDITION SALT THEREOF, FROM 0.67 TO 1.0 MOLAR EQUIVALENT OF A WATER SOLUBLE, PHYSIOLOGICALLY ACCEPTABLE MAGNESIUM SALT PER MOLE OF OXYTETRACYCLINE, AND SUFFICIENT OF A WATER SOLUBLE, PHYSIOLOGICALLY ACCEPTABLE BASE SELECTED FROM THE GROUP CONSISTING OF AMMONIA AND A PHYSIOLOGICALLY ACCEPTABLE, WATER SOLUBLE LOWER ALIPHATIC AMINE HAVING A DISSOCIATION CONSTANT OF GREATER THAN 10-6 TO RPOVIDE SAID COMPOSITION WITH A PH OF ABOUT 8.5 TO 9.5. 